Every single Justice Department inspector general who has led the office since it was created a quarter century ago agreed Tuesday that misconduct allegations against federal prosecutors should be handled by the department’s top watchdog and not by a separate internal unit that operates under the attorney general.

Unlike those in other major federal agencies, the Justice Department’s Office of the Inspector General isn’t allowed to investigate alleged misconduct by a massive chunk of the department’s employees. Instead, inquiries into the conduct of Justice Department lawyers in Washington and assistant U.S. attorneys across the country are handled by the Office of Professional Responsibility, an entity that has long been criticized for its lack of transparency.

Federal judges have railed against OPR, which one former federal prosecutor called a “roach motel” because cases “check in, but they don’t check out.” Even the man who helped create the office and ran it for 22 years said before his death in 2007 that he believed it should be abolished and its duties handed over to OIG.

An independent investigation by the nonprofit Project on Government Oversight found 650 infractions by Justice Department attorneys — more than 400 of them categorized as reckless or intentional — from fiscal years 2002 through 2013. The department itself does not disclose the names of lawyers investigated or the details of the cases.

It’s still unfathomable to me why the Justice Department keeps this information secret. The official explanation is that it’s to protect the professional privacy of the prosecutors OPR investigates. That just doesn’t fly. Not only are these public employees paid by taxpayers, they’re public employees who are given extraordinary power. Merely bringing charges can bankrupt a suspect, ruin his reputation and generally dissemble his life. Actually, even an investigation, without charges, can do all of those things. OPR’s approach to transparency appears to be, “Trust us, we’ve got this.” Plenty of studies have shown that they don’t. But even if OPR wasdoing an adequate job investigating and disciplining wayward prosecutors, it’s far too important a function to keep shielded from public and media scrutiny.

Eric Holder, like virtually every attorney general before him, supports the current structure.

“I am not supportive of any action that would put under the Inspector General that which is now in the responsibility of the Office of Professional Responsibility,” Holder said. “OPR has had, I think, a long and distinguished history of looking at these matters, recommending, where appropriate, punishment that has been carried out. They have a unique expertise. There are specific matters that I think only an OPR can handle. I have great respect for the Inspector General’s office, but I don’t think that the merger of those functions would be in the best interest of the Justice Department.”

Note Holder’s wording. It’s in the best interest of the Justice Department. That’s quite a bit different from what’s in the best interest of justice.